Comment 4 for bug 241991

Just an update, I sent it upstream:

http://bugzilla.gnome.org/show_bug.cgi?id=567671

This appears to be a case of "it's not a bug, it's a feature!" It happens when you navigate menu X and hover over a menu item Y causing submenu Z to pop up. Then if you move your cursor down menu X and towards the right a little bit, the delay will occur. This is intentional; it allows the user to move the mouse directly to a desired menu entry in Z without having to keep it inside the region of menu item Y first.

I have proposed reducing the default menu popdown delay to make this less bothersome in situations where it triggers incorrectly. Not sure if this will be deemed acceptable or not yet.